Contact device for electric circuit breakers



May 19, 1931. w. H. P ETERSEN 1,305,117

CONTACT DEVICE FOR ELECTRIC CIRCUIT BREAKERS Filed June 12, 1929 I v I w' ll 1 m fil E? Bye/2Z0)". h flhelm Hen/wing Peiersrv J76 Zorney Patented May 19, 1931 UNITED STATES PATENT, OFFICE SVENSKA ELEKTRISKA AKTIEBOLAGET, 0F ,VASTE RAS, SWEDEN, A CORPORATION OF SWEDEN CONTACT DEVICE FOR ELECTRIC CIRCUIT BREAKERS Application filed June 12, 1929, Serial No. 370,182, and in SWeden'Jule 23, 1928.

In electric circuit-breakers it is generally regarded as desirable that the contacts be so arranged that other portions thereof bear against each other in the final closed posi tion than those which first make contact during the closing and last leave each other dur ing the breaking operation, because the lastmentioned portions generally obtain a rough surface by reason of the burning from the arc. For this purpose, one or both of the co-operating contact members are often mounted resiliently so as to be rotatable to a certain extent and perform a rolling movement against each other during the closing operation. It is true that this arrangement relieves the surfaces roughened by the arcing, of the duty of normally carrying current,but it has generally the inconvenience to cause vibrations during the closing operation which may often cause a worse arcing than that accompanying the breaking. Further the said arcing always affects the same portions of the contacts whereby the irregularities of the surface here will finally be so great that they may have influence onthe contact between the normally acting contact surfaces.

The present invention relates to a contact device for circuit-breakers which is free from the aforesaid inconveniences. According to the invention, one .of the two co-operating contact members consists of a freely rotatable cylinder and the other of a contact finger bearing against said cylinder and so arranged with respect thereto that the portions normally making contact lie axially distant from the portions which are operative at the contact making and breaking instants.

A form of the invention is illustrated in the accompanying drawings in broken position as seen from beneath in Fig. 1 while Fig. 2 shows the same in side view, partially in section, in closed position, and Fig. 3 shows one of the contact members in end view.

A lever arm 1 rotatable about a pivot pin 2 carries a fork 3 which has bearings 4 for the rotatable contact cylinder 5 and is insulated from the arm 1 at 3. The cylinder 5 consists a middle portion of comparatively small diameter and two end portions 5' of larger diameter. It, co-operates with two contact fingerscomposed ofsprin s6 and contact pieces carried thereby, eac of the latter. consisting of an outerportion 7 intendedto bear against the enlarged end portion 5 of the cylinder 5 and an inner thicker portion 8 intended to bear against, the thinner portion of the cylinder 5., The

springs 6 are secured by means of brackets 6 to a common insulating member 6". .Durmg the closing operatlon the thicker portion 5 of the cylinder first meets the portion 7 of the contact fingers and preferably moves towards the latter under a very acute angle so as to cause no hammering which may be likely to cause vibrations. The cylinder then rolls along the contact piece 7 until its thinner portion meets the inner contact portion 8, also under a very small angle, and makes final contact therewith. At the breaking operation, the parts move in the opposite direction, and the final breaking occurs between the portions 5 and 7 so as to protect entirely the surfaces of the portions 5 and 8 against burns. The burns on the portion 5 are distributed along the whole periphery thereof so that many breaks may be per-, formed before the cylinder is so damaged" as to need replacing. Such a replacing is moreover easily effected.

Preferably two symmetrically arranged contact fingers 6, 7, 8 are provided to cooperate with each cylinder 5, as shown in the drawings, so that the current passes from one contact finger over the cylinder 5 to the other contact finger.

I claim as my invention 1. Electric contact device comprising a rotatable cylinder and a pair of contact fingers movable relatively to each other, said fingers bearing against said cylinder at the same side and bearing against one portion of said cylinder at the first contact and against another portion of said cylinder axially distant from theformer at the final contact.

2. Electric contact device comprising a rotatable cylinder having portions of different diameter and a pair of contact fingers having portions of different thickness adapted to bear against said cylinders at the same side thereof.

3. Electric contact device comprising a rotatable cylinder having portions of different diameter and a pair of contact fingers having portions of different thickness bearingagainst said cylinder at the same sidethereof, said cylinder and contact finger being movable towards each other and arranged to make contact first between a cylinder portion of one diameter and a finger portion of one thickness and then between a cylinder portion of another diameter and v a finger portion of another thickness.

4:. Electric contact device comprising a rotatable conducting cylinder and a pair of contact fingers movable Withrespect to each 7 [other and bearing against said cylinder at the same side thereof said fingers bearing against one portion of said cylinder at the 'first contact and against another portion of said cylinder at the final contact, one of said contact fingers serving as inlet and the other i as outlet for'the electric current.

In testimony whereof I have signed my name to this specification;

- ILHELM ENNINGPETE SEN] 

